High-pressure fuel reservoirs are most commonly used in diesel engines employing what are known as common-rail systems. In such systems, the fuel is compressed by means of a high-pressure pump to a pressure of more than 1000 to over 2000 bar and supplied to the high-pressure fuel reservoir. From this, pressure lines lead to the injectors of the individual combustion chambers of the internal combustion engine. Given the pressures that prevail, the high-pressure fuel reservoir is subject to a considerable mechanical load, which also fluctuates strongly during operation.
In order to achieve sufficient strength to withstand continuous pressure and continuous pulsing, in particular with a view to the higher injection pressures expected in the future, it makes sense to incorporate intrinsic pressure stresses into the surface of the inner bore of the high-pressure fuel reservoir. This can be done, for example, by means of internal shot peening. A disadvantage with this method, however, is the varying peening effect which occurs in the process at the internal intersecting edges to the line branches, which becomes visible as irregular rounding. On the other hand, an overly pronounced rounding of the internal cut edges is also disadvantageous.